Emulsion explosives used in commercial blasting operations are typically formed by mixing an emulsion comprising an aqueous solution of an oxidizer, a fuel and an emulsifier (hereafter referred to as an “intermediate emulsion”) with a suitable sensitising additive that renders the emulsion detonable. The result is a sensitised emulsion explosive. The intermediate emulsion is generally a high internal phase water-in-oil emulsion containing droplets of an oxidizer solution emulsified in a fuel.
Intermediate explosives and sensitised emulsion explosives are well known and described in the art. For example, U.S. Pat. No. 3,447,978 is master patent reference describing emulsions in term of individual components of emulsion blasting agents (non detonator sensitive), U.S. Pat. No. 4,149,917 is master patent reference for detonator sensitive emulsion blasting agents and U.S. Pat. No. 4,138,281 is the first patent describing emulsion manufacturing process of packaged detonator sensitive emulsions.
In order to achieve economies of scale and efficiencies the intermediate emulsion is usually manufactured in bulk at a centralised, dedicated facility and transported to the site of intended use or to a specialist plant for blending up as an emulsion explosive. That location may well be remote and quite possibly in a different country from where the intermediate explosive is manufactured.
Furthermore, with transportation in mind, the intermediate explosive is made to meet the UN non-explosive hazard classification. This requires the intermediate explosive to include a relatively large amount of water in the formulations. The water-diluted intermediate emulsions, besides being classified as non-explosive (Oxidizer class 5.1) also exhibits reduced sensitivity & explosives energies.
This manufacture and supply chain model has been commercially successful but, in recent times, there has been cause to reconsider it due to regulations relating to the security associated with manufacture and transport of explosives and explosives components.
It is also evident the process of supply and delivery of intermediate emulsions creates limitations and constraints in the applications on the customer sites. This is because due to varying customer needs, it is not easy to achieve specific performance characteristics, such as detonator sensitivity or high energy of the explosive products.
Against this background it would be desirable to be able to manufacture the intermediate emulsion and a corresponding emulsion explosive with suitably high performance on-site at the location of intended end use. However, this alternative approach is by no means straight forward as it brings with it various other practical issues. For example, the location of intended use can be remote and not easily accessible. Accordingly, it may not be feasible to transport and install large and/or complex manufacturing componentry. Any proposed local (on-site) manufacture will also need to have a suitably high production rate to cope with usage demand, and product quality must also be consistently high and predictable.